U.S. patent application number 10/674358 was filed with the patent office on 2004-06-17 for toner for developing electrostatic latent image.
This patent application is currently assigned to RICOH COMPANY, LTD.. Invention is credited to Saito, Takuya, Sugiyama, Tsunemi, Suzuki, Masanori, Takada, Takeshi, Watanabe, Yohichiroh, Yamashita, Hiroshi.
Application Number | 20040115551 10/674358 |
Document ID | / |
Family ID | 32281402 |
Filed Date | 2004-06-17 |
United States Patent
Application |
20040115551 |
Kind Code |
A1 |
Sugiyama, Tsunemi ; et
al. |
June 17, 2004 |
Toner for developing electrostatic latent image
Abstract
An improved toner comprises a binder resin comprising a
urea-modified polyester resin; a colorant master batch comprising a
colorant; a resin; and a pigment dispersant. The toner is prepared
by a method comprising dissolving or dispersing toner compositions
including a modified polyester resin capable of forming the
urea-modified polyester resin and the colorant master batch in an
organic solvent to provide a liquid; dispersing the liquid in an
aqueous medium including resin fine particles while reacting the
modified polyester resin with at least one of a crosslinker and an
elongation agent to provide particles; and washing the particles
after removing the organic solvent therefrom.
Inventors: |
Sugiyama, Tsunemi;
(Numazu-shi, JP) ; Yamashita, Hiroshi;
(Numazu-shi, JP) ; Watanabe, Yohichiroh;
(Fuji-shi, JP) ; Saito, Takuya; (Numazu-shi,
JP) ; Takada, Takeshi; (Numazu-shi, JP) ;
Suzuki, Masanori; (Shizuoka-ken, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
RICOH COMPANY, LTD.
Tokyo
JP
|
Family ID: |
32281402 |
Appl. No.: |
10/674358 |
Filed: |
October 1, 2003 |
Current U.S.
Class: |
430/109.4 ;
430/123.5; 430/137.1 |
Current CPC
Class: |
G03G 9/08755 20130101;
G03G 9/08764 20130101; G03G 9/0806 20130101 |
Class at
Publication: |
430/109.4 ;
430/124; 430/137.1 |
International
Class: |
G03G 009/087 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 1, 2002 |
JP |
2002-289090 |
Claims
What is claimed as new and desired to be secured by Letters Patent
of the United States is:
1. A toner comprising: a binder resin comprising a urea-modified
polyester resin; and a colorant master batch comprising: a
colorant; a resin; and a pigment dispersant, wherein the toner is
prepared by a method comprising: dissolving or dispersing a toner
composition comprising a modified polyester resin capable of
forming the urea-modified polyester resin and the colorant master
batch in an organic solvent, thereby forming a liquid; dispersing
the liquid in an aqueous medium comprising resin fine particles
while reacting the urea-modified polyester resin with at least one
of a crosslinker and an elongation agent to provide particles; and
washing the particles after removing the organic solvent
therefrom.
2. The toner of claim 1, wherein the pigment dispersant is present
in an amount of 1 to 30% by weight based on total weight of the
colorant.
3. The toner of claim 1, wherein the colorant master batch further
comprises a pigment dispersion auxiliary agent.
4. The toner of claim 1, wherein the colorant has a number-average
particle diameter of not greater than 0.5 .mu.m, and wherein a
ratio of particles of the colorant having a number-average particle
diameter not less than 0.7 .mu.m is not greater than 5% by
number.
5. The toner of claim 1, wherein the toner composition further
comprises an unmodified polyester resin, and wherein a weight ratio
(i/ii) of the urea-modified polyester resin (i) to the unmodified
polyester resin (ii) is from 5/95 to 25/75.
6. The toner of claim 1, further comprising a wax.
7. The toner of claim 1, wherein the toner has a glass transition
temperature of from 40 to 70.degree. C.
8. The toner of claim 1, wherein the toner has a volume-average
particle diameter of from 4 to 8 .mu.m, and wherein a ratio (Dv/Dn)
of the volume-average particle diameter (Dv) to the number-average
particle diameter (Dn) of the toner is not greater than 1.25.
9. The toner of claim 1, wherein the toner has an average
circularity of from 0.94 to 1.00.
10. The toner of claim 1, wherein the resin fine particles have an
average particle diameter of from 5 to 500 nm.
11. A developer comprising the toner according to claim 1.
12. An imaging forming method comprising: charging a photoreceptor;
irradiating the photoreceptor to form an electrostatic latent image
thereon; developing the electrostatic latent image with a toner
according to claim 1 to form a toner image on the photoreceptor;
transferring the toner image onto a transfer sheet; and fixing the
toner image on the transfer sheet.
13. A toner container containing the toner according to claim
1.
14. An image forming apparatus comprising: a charger for charging a
photoreceptor; an irradiator for irradiating the photoreceptor to
form an electrostatic latent image thereon; an image developer for
developing the electrostatic latent image with a toner according to
claim 1 to form a toner image on the photoreceptor; a transferer
for transferring the toner image onto a transfer sheet; and a fixer
for fixing the toner image on the transfer sheet.
15. A detachable process cartridge with an image forming apparatus
comprising: a photoreceptor; and a member selected from the group
consisting of chargers, image developers and cleaners, wherein the
image developers comprise a developer comprising the toner
according to claim 1.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a toner for developing an
electrostatic latent image, more particularly to a toner for
developing an electrostatic latent image formed on a photoreceptor,
and a process cartridge comprising the toner.
[0003] 2. Discussion of the Background
[0004] An electrophotographic apparatus or an electrostatic
recording apparatus adheres a toner onto an electrostatic latent
image formed on a photoreceptor, transfers the toner image onto a
transfer material and fixes the toner image on the transfer
material with a heat. A full color image is typically formed by
using a black, a yellow, a magenta and a cyan color toner. Each
color toner is developed and overlapped on a transfer material, and
heated and fixed at the same time to form a full color image on the
transfer material.
[0005] However, users who are used to printed images are not
satisfied with images produced by full-color copiers, and demand
higher definition and higher resolution images. Toners having a
small particle diameter and a narrow particle diameter distribution
are known.
[0006] A conventional toner is prepared by melting, mixing and
uniformly dispersing a colorant, a charge controlling agent and an
offset inhibitor in a thermoplastic resin, and by pulverizing and
classifying the mixture. Such methods of producing a toner tend to
produce toners having a wide particle diameter distribution range.
For example, fine particles having a diameter of not greater than 5
.mu.m and coarse particles having a diameter of not less than 20
.mu.m have to be removed by classifying, which has the drawback of
producing quite low yields. Particularly, in preparing a color
toner, it is difficult to uniformly disperse a colorant and a
charge controlling agent in a thermoplastic resin. An uneven
dispersion of the colorant and charge controlling agent has an
adverse effect on fluidity, developability, durability and the
ability of the resulting toner to provide a quality image.
[0007] Recently, to solve the problems of pulverizing methods, a
wet granulating method for producing toner has been suggested and
practiced. The wet granulating method can eliminate the need for a
conventional pulverizing process and a kneading process and
contributes to cost reductions by saving energy and production
time, and by improving process yield. Furthermore, the wet
granulating method produces a toner having a sharp particle
diameter distribution as well as a small particle diameter, which
contributes to the higher quality image produced by the toner.
Known methods include suspension polymerization methods, emulsion
polymerization methods and polymer suspension methods.
[0008] The suspension polymerization method is a method of
producing toner particles by suspending and polymerizing a
polymeric monomer, a polymerization initiator and toner components
such as colorants in an aqueous medium including a dispersant. The
problem with this method is that a polyester resin which is
preferably used for a full color toner cannot be used because the
binder resin is limited to a styrene-acrylic resin. In addition, it
is difficult to produce a toner having two peaks in its molecular
weight distribution to have both low-temperature fixability and hot
offset resistance with sensitive control. Also, the resulting toner
has poor cleanability because it has a spherical shape.
[0009] The emulsion polymerization method is a method of producing
a toner by emulsifying and polymerizing a polymerizing monomer and
a polymerization initiator in water including a surfactant to form
fine particles, and by agglomerating and fusion bonding the fine
particles. This method can produce an amorphous particulate toner,
which has better cleanability than a suspension polymerized toner.
However, it is as difficult to use a polyester resin and control
molecular weight in this method as it is in the suspension
polymerization method. In addition, a large amount of the
surfactant remains not only on the surface of the particles, but
also inside the particles, even after they have been washed with
water. Therefore, the resulting toner does not become stably
charged depending on the environment, and has a wide charge amount
distribution, and produces images with background fouling.
Furthermore, the remaining surfactant contaminates the
photoreceptor, charging roller, and developing roller, resulting in
deterioration of the original chargeability of these devices.
[0010] A polymer suspension method is a method of granulating a
polymer in water without a polymerization reaction, in which the
binder resin polymer and toner components are dispersed and
dissolved in a volatile solvent such as organic solvents having a
low boiling point. The mixture is emulsified in an aqueous medium
including a dispersant, the emulsified mixture is distilled and the
volatile solvent is removed. A polyester resin can be used in this
method. However, a crosslinked polymer resin cannot be used because
the method includes a step of dispersing or dissolving a toner
component in a solvent, and therefore this method cannot
sufficiently control the fixability of the resulting toner.
[0011] To ensure that the full color images produced by an
electrophotographic image forming method have as high a quality as
that of printed images, each color toner needs to have a wide color
reproducibility. To achieve this without encountering problems, a
colorant having good transparency, light resistance and heat
resistance is uniformly dispersed in a toner.
[0012] However, it is difficult to uniformly and finely disperse a
colorant by the above-mentioned wet granulating method because the
wet granulating method does not have a step for uniformly mixing
toner materials with a strong shearing force in a medium having a
high viscosity, as the kneading and pulverizing method does. In
addition, colorant particles are not stably dispersed in a liquid
even when uniformly dispersed in the initial stage of the
granulating process, and the colorant particles tend to agglomerate
again and be omnipresent in the interface between a toner grease
spot and water. When the colorant becomes largely agglomerated, the
color reproducibility and image density largely deteriorate. When
the colorant is omnipresent in an interface between a toner grease
spot and water, the resulting toner does not have stable
chargeability.
[0013] Japanese Laid-Open Patent Publication No. 11-231572
discloses a toner having a colorant dispersed by a synergist and a
polymer dispersant, in which a synergist which is a colorant
derivative is included to increase the interaction between the
colorant and polymer dispersant. Therefore, the dispersibility of
the colorant can be improved, but a colorant in a liquid cannot be
dispersed sufficiently.
[0014] For these reasons, there is a need for a toner for
developing an electrostatic latent image which does not require the
classifying process needed for a conventional pulverized toner, and
which has good cleanability, a small particle diameter, a narrow
particle diameter distribution, and is stably charged for a long
time. These properties largely contribute to providing high quality
images having high resolution and good tone reproducibility, high
colorability, high image density, high chromaticness and
transparency, and good light resistance without fading.
SUMMARY OF THE INVENTION
[0015] Accordingly, an object of the present invention is to
provide a toner for developing an electrostatic latent image which
does not require the classifying process needed for a conventional
pulverized toner, has good cleanability, a small particle diameter,
a narrow particle diameter distribution, and is stably charged for
a long time. These properties largely contributing to high quality
images having high resolution and good tone reproducibility, high
colorability, high image density, high chromaticness and
transparency, and good light resistance without fading.
[0016] Briefly this object and other objects of the present
invention as hereinafter will become more readily apparent can be
attained by a toner comprising: a binder resin which comprises a
urea-modified polyester resin; a colorant master batch comprising a
colorant; a resin; and a pigment dispersant. The toner is prepared
by a method comprising: dissolving or dispersing toner compositions
comprising a modified polyester resin capable of being the
urea-modified polyester resin and a colorant master batch in an
organic solvent, thereby producing a liquid; dispersing the liquid
in an aqueous medium comprising resin fine particles, while
reacting the modified polyester resin with at least one of a
crosslinker and an elongation agent to prepare particles; and
washing the particles after removing the organic solvent
therefrom.
[0017] Another object of the present invention is to provide a
process cartridge comprising the toner of the present
invention.
BRIEF DESCRIPTION OF THE DRAWING
[0018] FIG. 1 is a schematic view illustrating an embodiment of the
process cartridge of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Generally, the present invention provides a toner for
developing an electrostatic latent image, which does not require
the classifying process needed for a conventional pulverized toner,
and which has good cleanability, a small particle diameter, a
narrow particle diameter distribution, and is stably charged for a
long time. These properties largely contribute to providing high
quality images having high resolution and good tone
reproducibility, high colorability, high image density, high
chromaticness and transparency, good light resistance without
fading.
[0020] The present inventors have developed a method of producing a
toner which takes advantage of the benefits of the wet granulating
method, and yet solves the conventional problems. The method of the
present invention for producing a toner comprises dissolving or
dispersing toner compositions comprising a modified polyester resin
capable of forming urea groups in an organic solvent; reacting the
dissolved or dispersed toner compositions with a crosslinker and/or
an elongation agent in an aqueous medium comprising resin
particles; and washing the reacted toner compositions to removed
the solvent therefrom.
[0021] The present invention has the advantages of being capable of
producing a toner having a small particle diameter and a narrow
particle diameter distribution which are features of a conventional
toner produced by the wet granulating method, using a polyester
resin, easily controlling molecular weight by combining
(elongating) the polyester resin with a polyaddition reaction in
the process of granulating, crosslinking, increasing the
dispersibility of a pigment which easily adheres to a urea
combination (which is a polar group on the polyester chain) and
controlling the shape of the toner particles.
[0022] In the present invention, a polyester prepolymer (A) having
an isocyanate group is preferably used as the modified polyester
resin capable of forming urea groups. Specific examples of the
prepolymer (A) having an isocyanate group include a polymer formed
from the reaction between polyester having an active hydrogen atom
group formed by the polycondensation of a polyol (1) a
polycarboxylic acid (2), and polyisocyanate (3). Specific examples
of groups having an active hydrogen atom include a hydroxyl group
(an alcoholic hydroxyl group and a phenolic hydroxyl group), an
amino group, a carboxyl group, a mercapto group, etc. Preferably,
the active hydrogen atom group is an alcoholic hydroxyl group.
[0023] A diol (1-1) and polyol having 3 valences or more (1-2) can
be used as the polyol (1), and diol (1-1) alone or a mixture of
diol (1-1) and a small amount of polyol (1-2) are preferably used.
Specific examples of the diol (1-1) include alkylene glycols such
as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol,
1,4-butanediol, and 1,6-hexanediol; alkylene ether glycols such as
diethylene glycol, triethylene glycol, dipropylene glycol,
polyethylene glycol, polypropylene glycol and polytetramethylene
ether glycol; alicyclic diols such as 1,4-cyclohexanedimethanol and
hydrogenated bisphenol A; bisphenols such as bisphenol A, bisphenol
F and bisphenol S; adducts of the above-mentioned alicyclic diols
with an alkylene oxide such as ethylene oxide, propylene oxide and
butylene oxide; and adducts of the above-mentioned bisphenols with
an alkylene oxide such as ethylene oxide, propylene oxide and
butylene oxide. Preferably, the polyol (1) is selected from an
alkylene glycol having 2 to 12 carbon atoms and adducts of
bisphenol with an alkylene oxide. More preferably, the polyol (1)
is a mixture thereof. Specific examples of the polyol having 3
valences or more (1-2) include multivalent aliphatic alcohols
having 3 to 8 or more valences such as glycerin, trimethylolethane,
trimethylolpropane, pentaerythritol and sorbitol; phenols having 3
or more valences such as trisphenol PA, phenolnovolak,
cresolnovolak; and adducts of the above-mentioned polyphenol having
3 or more valences with an alkylene oxide.
[0024] A dicarboxylic acid (2-1) and a polycarboxylic acid having 3
or more valences (2-2) can be used as the polycarboxylic acid (2).
Dicarboxylic acid (2-1) alone, or a mixture of (2-1) and a small
amount of (2-2) are preferred. Specific examples of the
dicarboxylic acid (2-1) include alkylene dicarboxylic acids such as
succinic acid, adipic acid and sebacic acid; alkenylene
dicarboxylic acids such as maleic acid and fumaric acid; and
aromatic dicarboxylic acids such as phthalic acid, isophthalic
acid, terephthalic acid and naphthalene dicarboxylic acid. In
particular, alkenylene dicarboxylic acids having 4 to 20 carbon
atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms
are preferred. Specific examples of the polycarboxylic acid having
3 or more valences (2-2) include aromatic polycarboxylic acids
having 9 to 20 carbon atoms such as trimellitic acid and
pyromellitic acid. The polycarboxylic acid (2) can be formed from a
reaction between the polyol (1) and the above-mentioned acids
anhydride or lower alkyl esters such as a methyl ester, ethyl ester
and isopropyl ester.
[0025] The polyol (1) and polycarboxylic acid (2) are mixed such
that the equivalent ratio ([OH]/[COOH]) of the hydroxyl group [OH]
and a carboxylic group [COOH] is typically from 2/1 to 1/1,
preferably from 1.5/1 to 1/1 and more preferably from 1.3/1 to
1.02/1.
[0026] Specific examples of the polyisocyanate (3) include
aliphatic polyisocyanates such as tetramethylenediisocyanate,
hexamethylenediisocyanate and 2,6-diisocyanatemethylcaproate;
alicyclic polyisocyanates such as isophoronediisocyanate and
cyclohexylmethanediisocyanate; aromatic diisocyanates such as
tolylenedisocyanate and diphenylmethanediisocyanate; aromatic
aliphatic diisocyanates such as .alpha., .alpha., .alpha.',
.alpha.'-tetramethylxyl- ylenediisocyanate; isocyanurates; the
above-mentioned polyisocyanates blocked with phenol derivatives,
oxime and caprolactam; and their combinations.
[0027] The polyisocyanate (3) is mixed with a polyester such that
the equivalent ratio ([NCO]/[OH]) of the isocyanate group [NCO] and
the polyester having a hydroxyl group [OH] is typically from 5/1 to
1/1, preferably from 4/1 to 1.2/1 and more preferably from 2.5/1 to
1.5/1. When [NCO]/[OH] is greater than 5, the low temperature
fixability of the resultant toner deteriorates. When [NCO] has a
molar ratio less than 1, the urea content of the ester of the
modified polyester decreases and the hot offset resistance of the
resultant toner deteriorates. The content of the polyisocyanate (3)
in the polyester prepolymer (A) having a polyisocyanate group at
its end portion is from 0.5 to 40% by weight, preferably from 1 to
30% by weight and more preferably from 2 to 20% by weight. When the
content is less than 0.5% by weight, the hot offset resistance of
the resulting toner deteriorates and in addition the heat
resistance and low temperature fixability of the toner also
deteriorate. In contrast, when the content of the polyisocyanate
(3) is greater than 40% by weight, the low temperature fixability
of the resulting toner deteriorates.
[0028] The number of isocyanate groups in a molecule of the
polyester prepolymer (A) is at least 1, preferably from 1.5 to 3 on
average, and more preferably from 1.8 to 2.5 on average. When the
number of isocyanate groups is less than 1 per molecule of
polyester prepolymer (A), the molecular weight of the urea-modified
polyester decreases and the hot offset resistance of the resulting
toner deteriorates.
[0029] In the present invention, the elongation agent and/or
crosslinker are preferably the amines (B).
[0030] Specific examples of the amines (B) include diamines (B1),
polyamines (B2) having three or more amino groups, amino alcohols
(B3), amino mercaptans (B4), amino acids (B5) and blocked amines
(B6) in which the amines (B1-B5) mentioned above are blocked.
Specific examples of the diamines (B1) include aromatic diamines
(e.g., phenylene diamine, diethyltoluene diamine and
4,4'-diaminodiphenyl methane); alicyclic diamines (e.g.,
4,4'-diamino-3,3'-dimethyldicyclohexyl methane, diaminocyclohexane
and isophoron diamine); aliphatic diamines (e.g., ethylene diamine,
tetramethylene diamine and hexamethylene diamine); etc. Specific
examples of the polyamines (B2) having three or more amino groups
include diethylene triamine, triethylene tetramine. Specific
examples of the amino alcohols (B3) include ethanol amine and
hydroxyethyl aniline. Specific examples of the amino mercaptan (B4)
include aminoethyl mercaptan and aminopropyl mercaptan. Specific
examples of the amino acids include amino propionic acid and amino
caproic acid. Specific examples of the blocked amines (B6) include
ketimine compounds which are prepared by reacting one of the amines
B1-B5 mentioned above with a ketone such as acetone, methyl ethyl
ketone and methyl isobutyl ketone; oxazoline compounds, etc. Among
these compounds, diamines (B1) and mixtures in which a diamine is
mixed with a small amount of a polyamine (B2) are preferred.
[0031] The molecular weight of the urea-modified polyesters can
optionally be controlled with an elongation inhibitor, if desired.
Specific examples of the elongation inhibitor include monoamines
such as diethyle amine, dibutyl amine, butyl amine and lauryl
amine, and blocked amines, i.e., ketimine compounds prepared by
blocking the monoamines mentioned above.
[0032] The mixing ratio (i.e., the ratio [NCO]/[NHx]) of the amount
of the prepolymer (A) having an isocyanate group to the amine (B)
is from 1/2 to 2/1, preferably from 1.5/1 to 1/1.5 and more
preferably from 1.2/1 to 1/1.2. When the mixing ratio is greater
than 2 or less than 1/2, the molecular weight of the urea-modified
polyester (i) decreases, resulting in the deterioration of hot
offset resistance of the resulting toner. The urea-modified
polyester (i) of the present invention may include a urethane
functional group as well as a urea functional group. The molar
ratio (urea/urethane) of the urea functional groups to the urethane
functional groups is from 100/0 to 10/90, preferably from 80/20 to
20/80 and more preferably from 60/40 to 30/70. When the amount of
the urea functional groups is less than 10%, the hot offset
resistance of the resulting toner deteriorates.
[0033] The urea-modified polyester (i) can be produced by a method
such as a prepolymer method. The weight-average molecular weight of
the urea-modified polyester is not less than 10,000, preferably
from 20,000 to 10,000,000 and more preferably from 30,000 to
1,000,000. When the weight-average molecular weight is less than
10,000, the hot offset resistance of the resulting toner
deteriorates. The number-average molecular weight of the
urea-modified polyester is not particularly limited when the
below-mentioned unmodified polyester (ii) is used in combination
with the urea-modified polyester (i). Namely, the weight-average
molecular weight of the urea-modified polyester resins has priority
over the number-average molecular weight thereof. However, when the
urea-modified polyester (i) is used alone, the number-average
molecular weight is from 2,000 to 15,000, preferably from 2,000 to
10,000 and more preferably from 2,000 to 8,000. When the
number-average molecular weight is greater than 20,000, the low
temperature fixability of the resulting toner deteriorates, and in
addition the glossiness of full color images produced with the
resulting toner deteriorates.
[0034] In the present invention, not only the urea-modified
polyester (i) alone but also the unmodified polyester (ii) may be
included as a toner binder with the urea-modified polyester (i). A
combination thereof improves the low temperature fixability of the
resulting toner and the glossiness of color images produced
thereby, and the combination is more preferred than the
urea-modified polyester (i) alone. Suitable unmodified polyesters
(ii) include polycondensation products of the polyol (1) and
polycarboxylic acid (2) similar to the urea-modified polyester (i)
and specific examples thereof are the same as those of the
urea-modified polyester (i). In addition, for the urea-modified
polyester (i), not only the unmodified polyester (ii) but also
polyester resins modified by functional groups such as urethane
functional groups, other than urea functional groups, can also be
used together. It is preferred that the urea-modified polyester (i)
at least partially mixed with the unmodified polyester (ii) to
improve the low temperature fixability and hot offset resistance of
the resulting toner. Therefore, the urea-modified polyester (i)
preferably has a structure similar to that of the unmodified
polyester (ii). The mixing ratio (urea-modified polyester
(i)/unmodified polyester) of the urea-modified polyester (i) and
unmodified polyester is from 5/95 to 80/20, preferably from 5/95 to
30/70, more preferably from 5/95 to 25/75, and even more preferably
from 7/93 to 20/80. When the urea-modified polyester (i) is less
than 5%, the hot offset resistance deteriorates, and in addition,
it is disadvantageous to have both high temperature preservability
and low temperature fixability.
[0035] The unmodified polyester (ii) usually has a peak molecular
weight of from 1,000 to 30,000, preferably from 1,500 to 10,000,
and more preferably from 2,000 to 8,000. When the peak molecular
weight is less than 1,000, high temperature preservability of the
resultant toner deteriorates. When the peak molecular weight is
greater than 10,000, the low temperature fixability of the
resulting toner deteriorates. The unmodified polyester (ii)
preferably has a hydroxyl value of not less than 5, more preferably
of from 10 to 120, and furthermore preferably of from 20 to 80.
When the hydroxyl value is less than 5, it is difficult for the
resultant toner to have both high temperature preservability and
low temperature fixability. The unmodified polyester (ii)
preferably has an acid value of from 1 to 30, and more preferably
from 5 to 20. An unmodified polyester (ii) having such acid values
tends to be negatively charged. When the hydroxyl value and acid
value are greater than 120 and 30 respectively, the resulting toner
tends to be affected by high or low temperature and humidity
environments, and therefore tends to produce deteriorated
images.
[0036] In the present invention, a masterbatch of a colorant is
provided by previously kneading a colorant with at least a binder
resin and a pigment dispersant in the presence of an organic
solvent or water. The colorant and binder resin sufficiently adhere
to each other and the colorant is effectively and stably dispersed
even after any production process. The resulting toner includes
well dispersed colorant, a small dispersion diameter thereof and
has good transparency.
[0037] Specific examples of the binder resin include the modified
and unmodified polyester resins mentioned above; styrene polymers
and substituted styrene polymers such as polystyrene,
poly-p-chlorostyrene and polyvinyltoluene; styrene copolymers such
as styrene-p-chlorostyrene copolymers, styrene-propylene
copolymers, styrene-vinyltoluene copolymers,
styrene-vinylnaphthalene copolymers, styrene-methyl acrylate
copolymers, styrene-ethyl acrylate copolymers, styrene-butyl
acrylate copolymers, styrene-octyl acrylate copolymers,
styrene-methyl methacrylate copolymers, styrene-ethyl methacrylate
copolymers, styrene-butylmethacrylate copolymers, styrene-methyl
.alpha.-chloromethacrylate copolymers, styrene-acrylonitrile
copolymers, styrene-vinyl methyl ketone copolymers,
styrene-butadiene copolymers, styrene-isoprene copolymers,
styrene-acrylonitrile-indene copolymers, styrene-maleic acid
copolymers and styrene-maleic acid ester copolymers; and other
resins such as polymethyl methacrylate, polybutylmethacrylate,
polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene,
polyesters, epoxy resins, epoxy polyol resins, polyurethane resins,
polyamide resins, polyvinyl butyral resins, acrylic resins, rosin,
modified rosins, terpene resins, aliphatic or alicyclic hydrocarbon
resins, aromatic petroleum resins, chlorinated paraffin, paraffin
waxes, etc. These resins may be used individually or in
combination.
[0038] Specific examples of the method of previously kneading a
mixture of a binder resin, a colorant and a pigment dispersant with
an organic solvent or water include a method of mixing a binder
resin, a colorant, a pigment dispersant and an organic solvent with
a blending device such as a Henschel mixer; and kneading the
mixture with a kneader such as two-roll and three-roll mills at a
lower temperature than the melting point of the binder resin.
Specific examples of the organic solvent include typical organic
solvents, in view of the solubility of the binder resin in these
solvents. Particularly preferred solvents include, for example,
acetone, toluene, butanone and the like solvents, in view of the
dispersibility of the colorant therein.
[0039] In addition, flushing methods can be used, in which an
aqueous paste including a colorant is mixed with a resin solution
of an organic solvent to transfer the colorant to the resin
solution, and then the aqueous liquid and organic solvent are
separated and removed. These flushing methods may be preferred
because the resulting wet cake of the colorant can be used as it
is. Of course, a dry powder which is prepared by drying the wet
cake can also be used as a colorant. In this case, a three-roll
mill is preferably used for kneading the mixture by the application
of high shear stress.
[0040] Known pigment dispersion auxiliaries may also be included in
the master batch to further increase dispersion of the colorant in
the resin.
[0041] These methods not only provide colorants with a small
particle diameter, but also increase the uniformity of the
dispersion, and therefore the color reproducibility of a projected
image by an OHP is further improved.
[0042] Furthermore, the colorant of the toner of the present
invention preferably has a number-average particle diameter not
greater than 0.5 .mu.m, more preferably not greater than 0.4 .mu.m,
and furthermore preferably not greater than 0.3 .mu.m. When the
number-average particle diameter is greater than 0.5 .mu.m, the
colorant does not have a sufficient dispersibility and the
resulting toner does not have targeted transparency. The colorant
having a number-average particle diameter of not less than 0.7
.mu.m is preferably not greater than 5 number %.
[0043] A colorant having a fine particle diameter of less than 0.1
.mu.m is basically considered not to have an adverse effect on
light reflection and absorption of the resulting toner.
[0044] A colorant having a particle diameter of less than 0.1 .mu.m
contributes to the transparency of an OHP sheet having good color
reproducibility and image fixability. To the contrary, a large
number of the colorants having a particle diameter greater than 0.5
.mu.m tend to essentially deteriorate the brightness and
chromaticness of a projected image on an OHP sheet.
[0045] Furthermore, a large amount of the colorants having a
particle diameter greater than 0.5 .mu.m are released from a
surface of the toner particle, and tend to cause various problems
such as background development, drum contamination and poor
cleaning. When such a toner is used in a two-component developer,
the carrier is contaminated and quality images are difficult to
produce in a stable manner when many images are durably produced.
Of course, good color reproducibility and uniform chargeability of
the toner cannot be expected.
[0046] Suitable colorants for the toner of the present invention
include known dyes and pigments. Specific examples of the colorants
include carbon black, Nigrosine dyes, black iron oxide, Naphthol
Yellow S, Hansa Yellow (10G, 5G and G), Cadmium Yellow, yellow iron
oxide, loess, chrome yellow, Titan Yellow, polyazo yellow, Oil
Yellow, Hansa Yellow (GR, A, RN and R), Pigment Yellow L, Benzidine
Yellow (G and GR), Permanent Yellow (NCG), Vulcan Fast Yellow (5G
and R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazane Yellow
BGL, isoindolinone yellow, red iron oxide, red lead, orange lead,
cadmium red, cadmium mercury red, antimony orange, Permanent Red
4R, Para Red, Fire Red, p-chloro-o-nitroaniline red, Lithol Fast
Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent
Red (F2R, F4R, FRL, FRLL and F4RH), Fast Scarlet VD, Vulcan Fast
Rubine B, Brilliant Scarlet G, Lithol Rubine GX, Permanent Red F5R,
Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine
Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B,
BON Maroon Light, BON Maroon Medium, Eosin Lake, Rhodamine Lake B,
Rhodamine Lake Y, Alizarine Lake, Thioindigo Red B, Thioindigo
Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, polyazo red,
Chrome Vermilion, Benzidine Orange, perynone orange, Oil Orange,
cobalt blue, cerulean blue, Alkali Blue Lake, Peacock Blue Lake,
Victoria Blue Lake, metal-free Phthalocyanine Blue, Phthalocyanine
Blue, Fast Sky Blue, Indanthrene Blue (RS andBC), Indigo,
ultramarine, Prussianblue, AnthraquinoneBlue, Fast Violet B, Methyl
Violet Lake, cobalt violet, manganese violet, dioxane violet,
Anthraquinone Violet, Chrome Green, zinc green, chromium oxide,
viridian, emerald green, Pigment Green B, Naphthol Green B, Green
Gold, Acid Green Lake, Malachite Green Lake, Phthalocyanine Green,
Anthraquinone Green, titanium oxide, zinc oxide, lithopone and the
like. These materials may be used alone or in combination.
[0047] The content of the colorant in the toner is preferably from
1 to 15% by weight, and more preferably from 3 to 10% by weight,
based on total weight of the toner.
[0048] Any known pigment dispersants and pigment dispersion
auxiliaries can be used in the present invention. To stabilize a
dispersion of fine particles in a liquid, a method of increasing a
potential energy barrier to prevent mutual contact of the particles
or a method of using the steric hindrance effect of a term molecule
adhered to the surface of the particles so as to prevent particles
from becoming so close to each other that the mutual Van der Waal's
forces of the particles are available. The dispersion medium of the
present invention for the colorant may be an organic solvent which
includes a dissolved binder resin. Electrostatic repulsion cannot
be expected from such a non-aqueous dispersion medium because of
its low permittivity. Therefore, a polymeric dispersant is
preferred. In particular, the polymeric dispersant preferably has a
functional group having a strong interaction with the surface
molecules of the colorant, and has a chemical structure such that a
segment elongated in the dispersion medium exerts its steric
hindrance repulsion after adhering to the surface of the colorant.
In particular, the polymeric dispersant preferably has a functional
group at its end. Commercially available SOLSPERSE is preferably
used as the polymeric dispersant.
[0049] The colorant preferably includes pigment dispersants and
pigment dispersion auxiliaries in an amount of from 1 to 30% by
weight based on total weight of the colorant.
[0050] Specific examples of the pigment dispersants of the present
invention include known polymeric dispersants such as polyester
resins, polycaprolactone resins, acrylic resins, unsaturated
polyester resins, photosensitive monomers having a (metha)acryloyl
group and oligomers. In addition, polyesteracrylate or its
hydrolysates, polyester (meth) acrylate or its hydrolysates,
polyvinylacetate or partially saponified polyvinylacetate,
polyvinylphenol, phenolnovolak resins, polystyrene,
polyvinylbutyral, polychloroprene, polyvinylchloride,
polyethylenechloride, polypropylenechloride, polyvinylpyrrolidone,
copolymers of styrene and maleic anhydride or their half esters,
and additional polymers prepared from copolymerizable monomers such
as acrylic acid, (meth)acrylic acid, acrylate esters,
(meth)acrylate esters, acrylamide, (meth)acrylamide, acrylonitrile,
and (meth)acrylonitrile. In view of the chargeability of the
resultant toner and the dispersibility with a toner binder, similar
resins to the toner binder are preferred.
[0051] The pigment dispersion auxiliaries of the present invention
are not particularly limited provided that they have a strong
interaction with the pigment dispersant as well as the pigment.
However, derivatives or precursors of a pigment having a structure
in common with the pigment are preferred because of their high
affinity with the pigment. In addition, the derivatives or
precursors of the pigment preferably have a polar functional group
having high affinity with a pigment dispersant because of the
strong interaction of the polar functional group with the pigment
dispersant. The interaction between the pigment dispersants and
pigment dispersion auxiliaries may be hydrogen bonding interaction
or an acid-base interaction. The pigment dispersion auxiliaries
preferably have functional groups such as hydroxyl groups and amide
groups to enhance the hydrogen bonding interaction. In addition,
the pigment dispersion auxiliaries preferably have basic functional
groups such as amino groups when the pigment dispersant has an
acidic functional group, and the pigment dispersion auxiliaries
preferably have acidic functional groups such as carboxyl groups
and sulfonate groups when the pigment dispersant has a basic
functional group.
[0052] The toner of the present invention may include a wax
together with a toner binder and a colorant. Specific examples of
the wax include known waxes, e.g., polyolefin waxes such as
polyethylene wax and polypropylene wax; long chain carbon hydrides
such as paraffin wax and sasol wax; and waxes including carbonyl
groups. Among these waxes, the waxes including carbonyl groups are
preferred. Specific examples thereof include polyesteralkanate
waxes such as carnauba wax, montan wax,
trimethylolpropanetribehenate, pentaelislitholtetrabehenate,
pentaelislitholdiacetatedibehenate, glycerinetribehenate and
1,18-octadecanedioldistearate; polyalkanolesters such as
tristearyltrimellitate and distearylmaleate; polyamidealkanates
such as ethylenediaminebehenylamide; polyalkylamides such as
tristearylamidetrimellitate; and dialkylketones such as
distearylketone. Among these waxes having a carbonyl group,
polyesteralkanates are preferred. The wax of the present invention
usually has a melting point of from 40 to 160.degree. C.,
preferably of from 50 to 120.degree. C., and more preferably of
from 60 to 90.degree. C. A wax having a melting point of less than
40.degree. C. has an adverse effect on its high temperature
preservability, and a wax having a melting point of greater than
160.degree. C. tends to cause cold offset of the resulting toner
when fixed at a low temperature. In addition, the wax preferably
has a melting viscosity of from 5 to 1,000 cps, and more preferably
of from 10 to 100 cps when measured at a temperature higher by
20.degree. C. than the melting point. A wax having a melting
viscosity greater than 1,000 cps makes it difficult to improve the
hot offset resistance and the low temperature fixability of the
resulting toner.
[0053] The content of the wax in the toner is preferably from 0 to
40% by weight, and more preferably from 3 to 30% by weight.
[0054] The toner of the present invention preferably has a glass
transition temperature (Tg) of from 40 to 70.degree. C., and more
preferably of from 45 to 65.degree. C. When the glass transition
temperature is less than 40.degree. C., the high temperature
preservability of the resulting toner deteriorates. When the Tg of
the toner is greater than 70.degree. C., the low temperature
fixability thereof becomes insufficient. Due to the presence of the
urea-modified polyester, the toner of the present invention has
better high temperature preservability than known toners having a
polyester binder resin, even though the glass transition
temperature is low. The toner binder preferably has a temperature
(TG') of not less than 100.degree. C., and more preferably of from
110 to 200.degree. C. at which temperature the storage modulus of
the toner binder is 10,000 dyne/cm.sup.2 at a measuring frequency
of 20 Hz. When the TG' of the toner binder is less than 100.degree.
C., the hot offset resistance of the resulting toner deteriorates.
The toner binder preferably has a temperature (T.eta.) of not
greater than 180.degree. C., and more preferably of from 90 to
160.degree. C. at which temperature the viscosity of the toner
binder is 1,000 poise at a measuring frequency of 20 Hz. When the
T.eta. is greater than 180.degree. C., the low temperature
fixability of the resulting toner deteriorates. Namely, TG' is
preferably higher than T.eta. in view of the compatibility between
the hot offset resistance and the low temperature fixability, i.e.,
a difference between TG' and T.eta. (TG'-T.eta.) is preferably not
less than 0.degree. C., more preferably not less than 10.degree.
C., and furthermore preferably not less than 20.degree. C. The
upper limit of the difference is not particularly limited. In
addition, in view of compatibility between the high temperature
preservability and the low temperature fixability, the difference
between T.eta. and Tg is preferably from 0 to 100.degree. C., more
preferably from 10 to 90.degree. C., and particularly preferably
from 20 to 80.degree. C.
[0055] The toner of the present invention preferably has a specific
shape and a distribution thereof. An amorphous toner having an
average circularity of less than 0.94 and being too far from being
spherical does not have sufficient transferability and produce high
quality images without toner scattering. Various methods for
measuring the shape may be used. For example, an optical detecting
belt passing a suspension liquid including a particulate material
through a plate image detecting belt and optically detecting an
image of the particulate material with a CCD camera is preferred.
The circularity is a value calculated by dividing the
circumferential length of a circle having an equivalent area to a
projected area obtained by this method with a circumferential
length of an actual particulate material.
[0056] A toner having an average circularity of from 0.94 to 1.00
is effectively used to form fine images with proper density. The
toner preferably has an average circularity of from 0.98 to 1.00,
and not greater than 10% of particles have a circularity of less
than 0.95. The average circularity is measured by a flow-type
particle image analyzer such as FPIA-2000 from SYSMEX CORP.
[0057] Specifically, 0.1 to 0.5 ml of a detergent, preferably an
alkylbenzenesulfonic acid salt as a dispersant is added to 100 to
150 ml of water from which impure solid matter has previously been
removed, and a further 0.1 to 0.5 g of a measurement sample is
added thereto. The suspension liquid including the sample is
dispersed by an ultrasonic disperser for about 1 to 3 min until the
dispersed liquid has a concentration of from 3,000 to 10,000 .mu.l,
and is measure by the flow-type particle image analyzer.
[0058] The toner of the present invention preferably has a
volume-average particle diameter (Dv) of from 4 to 8 .mu.m and a
ratio thereof to a number-average particle diameter (Dn) thereof
(Dv/Dn) of not greater than 1.25, and more preferably of from 1.10
to 1.25. Such a toner has good high temperature preservability, low
temperature fixability and hot offset resistance, and particularly
produces images having good glossiness when used in a full-color
copier. Further, when used in a two-component developer, even after
the toner is consumed and fed for a long time, the toner particle
diameter has less variation. In addition, even being after agitated
in an image developer for a long time, the toner has good and
stable developability. When used in a one-component developer, even
after the toner is consumed and fed for a long time, toner filming
over the developing roller and toner adherence over a blade for
making a thin layer of the toner do not occur. In addition, even
after being agitated in an image developer for a long time, the
toner has good and stable developability.
[0059] Generally, the smaller the particle diameter of the toner,
the better it produces high resolution and quality images. However,
small particle diameters are a disadvantage for transferability and
cleanability. When the Dv is less than the above-mentioned range,
the toner in a two-component developer adheres to a surface of a
carrier due to long agitation in an image developer, resulting in
deterioration of the chargeability of the carrier. The toner in a
one-component developer tends to cause filming over a developing
roller and adheres to a member such as a blade.
[0060] These phenomena also occur when the content of fine
particles in the toner is greater than the above-mentioned
range.
[0061] When the Dv is greater than the above-mentioned range, the
Dv tends to vary much and it is difficult to produce high
resolution and quality images. In addition, when Dv/Dn is greater
than 1.25, a similar problem occurs.
[0062] The toner of the present invention may optionally include a
charge controlling agent. Materials almost colorless or white are
preferred because colored materials cause a color change in the
resulting toner. Specific examples of the charge controlling agent
include known charge controlling agents such as triphenylmethane
dyes, chelate compounds of molybdic acid, Rhodamine dyes,
alkoxyamines, quaternary ammonium salts (including
fluorine-modified quaternary ammonium salts), alkylamides, phosphor
or compounds including phosphor, tungsten or compounds including
tungsten, fluorine-containing activators, metal salts of salicylic
acid, salicylic acid derivatives, etc. Specific examples of
commercially available charge controlling agents include BONTRON
P-51 (quaternary ammonium salt), E-82 (metal complex of
oxynaphthoic acid), E-84 (metal complex of salicylic acid), and
E-89 (phenolic condensationproduct),
whicharemanufacturedbyOrientChemical Industries Co., Ltd.; TP-302
and TP-415 (molybdenum complex of quaternary ammonium salt), which
are manufactured by Hodogaya Chemical Co., Ltd.; COPY CHARGE PSY
VP2038 (quaternary ammonium salt), COPY BLUE (triphenyl methane
derivative), COPY CHARGE NEG VP2036 and NX VP434 (quaternary
ammonium salt), which are manufactured by Hoechst AG; LRA-901, and
LR-147 (boron complex), which are manufactured by Japan Carlit Co.,
Ltd.; copper phthalocyanine, perylene, quinacridone, azo pigments
and polymers having a functional group such as a sulfonate group, a
carboxyl group, a quaternary ammonium group, etc.
[0063] The content of the charge controlling agent depends on the
species of the binder resin used, whether or not an additive is
added and the toner manufacturing method (such as dispersion
method), and is not particularly limited. However, the amount of
the charge controlling agent is typically from 0.1 to 10 parts by
weight, and preferably from 0.2 to 5 parts by weight, per 100 parts
by weight of the binder resin included in the toner. When the
amount is too high, the toner has too large an amount of charge,
and thereby the electrostatic force of a developing roller
attracting the toner increases, resulting in a deterioration of the
fluidity of the toner and a decrease of the image density of toner
images. These charge controlling agents can be dissolved and
dispersed after kneading and heating them with a master batch
pigment and resin, and can be added when directly dissolved and
dispersed in an organic solvent or can be fixed on a toner surface
after the toner particles are produced.
[0064] Resin fine particles are added to the toner of the present
invention. Any thermoplastic and thermosetting resins can be used
provided they can form an aqueous dispersion. Specific examples of
the resins include vinyl resins, polyurethane resins, epoxy resins,
polyester resins, polyamide resins, polyimide resins, silicon
resins, phenol resins, melamine resins, urea resins, aniline
resins, ionomer resins and polycarbonate resins. These resins may
be used in combination. Among these resins, vinyl resins,
polyurethane resins, epoxy resins, polyester resins and their
combinations are preferred because an aqueous dispersion of fine
spheric resin particles can easily be obtained.
[0065] Specific examples of the vinyl resins include polymers
formed of homopolymerized or copolymerized vinyl monomers such as
styrene-(meth)acrylate ester resins, styrene-butadiene copolymers,
(meth)acrylic acid-esteracrylate polymers, styrene-acrylonitrile
copolymers, styrene-maleic acid anhydride copolymers and
styrene-(meth)acrylic acid copolymers.
[0066] In the present invention, the resin fine particles
preferably have an average particle diameter of from 5 to 500
nm.
[0067] In organic fine particles are preferably used as an external
additive for improving fluidity, developability and chargeability
of the colored particles of the present invention. The inorganic
fine particles preferably have a primary particle diameter of from
5 nm to 2 .mu.m, and more preferably from 5 nm to 500 nm. In
addition, the specific surface area of the inorganic fine particles
measured by the BET method is preferably from 20 to 500 m.sup.2/g.
The amount of the external additive is preferably from 0.01 to 5%
by weight, and more preferably from 0.01 to 2.0% by weight, based
on total weight of the toner composition. Specific examples of the
inorganic fine particles include silica, alumina, titanium oxide,
barium titanate, magnesium titanate, calcium titanate, strontium
titanate, zinc oxide, tin oxide, quartz sand, clay, mica,
sand-lime, diatom earth, chromium oxide, cerium oxide, red iron
oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium
sulfate, barium carbonate, calcium carbonate, silicon carbide,
silicon nitride, etc.
[0068] Other than these materials, polymer fine particles such as
polystyrene formed by a soap-free emulsifying polymerization, a
suspension polymerization or a dispersing polymerization,
methacrylate ester or acrylate ester copolymers, silicone resins,
benzoguanamine resins, polycondensation fine particles such as
nylon and polymer particles of thermosetting resins can be
used.
[0069] These fluidizers, i.e., surface treatment agents can
increase hydrophobicity and prevent deterioration of the fluidity
and chargeability of the resulting toner even in high humidity.
Specific examples of surface treatment agents include silane
coupling agents, silylating agents, silane coupling agents having
an alkyl fluoride group, organic titanate coupling agents,
aluminium coupling agents silicone oils and modified silicone
oils.
[0070] The toner of the present invention may include a
cleanability improver for removing the developer remaining on the
photoreceptor and the first transfer medium after transferring.
Specific examples of the cleanability improver include fatty acid
metallic salts such as zinc stearate, calcium stearate and stearic
acid; and polymer fine particles prepared by a soap-free
emulsifying polymerization method such as polymethylmethacrylate
fine particles and polystyrene fine particles. The polymer fine
particles comparatively have a narrow particle diameter
distribution and preferably have a volume-average particle diameter
of from 0.01 to 1 .mu.m.
[0071] The toner binder of the present invention can be prepared,
for example, by the following method. Polyol (1) and polycarboxylic
acid (2) are heated to a temperature of from 150 to 280.degree. C.
in the presence of a known catalyst such as tetrabutoxy titanate
and dibutyltinoxide. Then water generated is removed, under reduced
pressure if desired, to provide a polyester resin having a hydroxyl
group. Then the polyester resin is reacted with polyisocyanate (3)
at a temperature of from 40 to 140.degree. C. to provide a
prepolymer (A) having an isocyanate group. Then, the prepolymer (A)
is reacted with an amine (B) at a temperature of from 0 to
140.degree. C., to provide a urea-modified polyester (i). A solvent
can be used if desired when the polyisocyanate, and A and B are
reacted. Suitable solvents include solvents which do not react with
a polyisocyanate. Specific examples of such solvents include
aromatic solvents such as toluene and xylene; ketones such as
acetone, methyl ethyl ketone and methyl isobutyl ketone; esters
such as ethyl acetate; amides such as dimethylformamide and
dimethylacetoaminde; ethers such as tetrahydrofuran. When a
polyester which does not have a urea functional group (ii) is used
in combination with the urea-modified polyester, polyester (ii) is
prepared by a method similar to that used for preparing the
polyester resins having a hydroxyl group, and the polyester (ii) is
added to the solution of the polyester (i) after the reaction of
forming the polyester (i) has been completed.
[0072] The toner of the present invention is produced by the
following method, but the method is not limited thereto.
[0073] The aqueous medium of the present invention includes water
alone and mixtures of water with a solvent which can be mixed with
water. Specific examples of the solvent include alcohols such as
methanol, isopropanol and ethylene glycol; dimethylformamide;
tetrahydrofuran; cellosolves such as methyl cellosolve; and lower
ketones such as acetone and methyl ethyl ketone.
[0074] The toner of the present invention can be prepared by
reacting a dispersion formed of the prepolymer (A) having an
isocyanate group with (B) or using the previously prepared
urea-modified polyester (i). As a method of stably preparing a
dispersion formed of the urea-modified polyester (i) or the
prepolymer (A) in an aqueous medium, a method of including toner
constituents such as the urea-modified polyester (i) or the
prepolymer (A) into an aqueous medium and dispersing them upon
application of shear stress is preferred. A prepolymer (A) and
other toner constituents such as colorants, master batch pigments,
release agents, charge controlling agents, unmodified polyester
resins, etc. may be added into an aqueous medium at the same time
when the dispersion is prepared. However, it is preferable that the
toner constituents are previously mixed and then the mixed toner
constituents are added to the aqueous liquid at the same time. In
addition, colorants, release agents, charge controlling agents,
etc., are not necessarily added to the aqueous dispersion before
particles are formed, and may be added thereto after particles are
prepared in the aqueous medium. A method of dyeing particles
previously formed without a colorant by a known dying method can
also be used.
[0075] The dispersion method is not particularly limited, and low
speed shearing methods, high-speed shearing methods, friction
methods, high-pressure jet methods, ultrasonic methods, etc. may be
used. Among these methods, high-speed shearing methods are
preferably used because particles having a particle diameter of
from 2 to 20 Am can be easily prepared. At this point, the particle
diameter (2 to 20 .mu.m) means a particle diameter of particles
including a liquid. When a high-speed shearing type dispersion
machine is used, the rotation speed is not particularly limited,
but the rotation speed is typically from 1,000 to 30,000 rpm, and
preferably from 5,000 to 20,000 rpm. The dispersion time is not
also particularly limited, but is typically from 0.1 to 5 minutes.
The temperature in the dispersion process is typically from 0 to
150.degree. C. (under pressure), and preferably from 40 to
98.degree. C. When the temperature is relatively high, the
urea-modified polyester (i) or prepolymer (A) can easily be
dispersed because the dispersion formed thereof has a low
viscosity.
[0076] The amount of the aqueous medium to 100 parts by weight of
the toner constituents including the urea-modified polyester (i) or
prepolymer (A) is typically from 50 to 2,000 parts by weight, and
preferably from 100 to 1,000 parts by weight. When the content is
less than 50 parts by weight, the dispersion of the toner
constituents in the aqueous medium is not satisfactory, and thereby
the resulting mother toner particles do not have the desired
particle diameter. In contrast, when the amount of the aqueous
medium is greater than 2,000, the production cost increases. A
dispersant can preferably be used to prepare a stably dispersed
dispersion including particles having a sharp particle diameter
distribution.
[0077] To synthesize the urea-modified polyester (i) from the
prepolymer (A), the amines (B) may be added to the toner
constituents before being dispersed in an aqueous medium or after
being dispersed. In this case, the urea-modified polyester is
formed on a surface of the toner by priority and a concentration
gradient can be formed in particles.
[0078] Specific examples of the dispersants used to emulsify and
disperse an oil phase for a liquid including water, in which the
toner constituents are dispersed, include anionic surfactants such
as alkylbenzene sulfonic acid salts, .alpha.-olefin sulfonic acid
salts, and phosphoric acid salts; cationic surfactants such as
amine salts (e.g., alkyl amine salts, aminoalcohol fatty acid
derivatives, polyamine fatty acid derivatives and imidazoline), and
quaternary ammonium salts (e.g., alkyltrimethyl ammonium salts,
dialkyldimethyl ammonium salts, alkyldimethyl benzyl ammonium
salts, pyridinium salts, alkyl isoquinolinium salts and
benzethonium chloride); nonionic surfactants such as fatty acid
amide derivatives, polyhydric alcohol derivatives; and ampholytic
surfactants such as alanine, dodecyldi (aminoethyl) glycin, di)
octylaminoethyle) glycin, and N-alkyl-N,N-dimethylammonium
betaine.
[0079] A surfactant having a fluoroalkyl group can provide a
dispersion having good dispersibility even when a small amount of
the surfactant is used. Specific examples of anionic surfactants
having a fluoroalkyl group include fluoroalkyl carboxylic acids
having from 2 to 10 carbon atoms and their metal salts, disodium
perfluorooctanesulfonylglutamate, sodium
3-{omega-fluoroalkyl(C6-C11)oxy}-1-alkyl(C3-C4) sulfonate, sodium
3-{omega-fluoroalkanoyl(C6-C8)-N-ethylamino}-1-propanesulfonate,
fluoroalkyl(C11-C20) carboxylic acids and their metal salts,
perfluoroalkylcarboxylic acids and their metal salts,
perfluoroalkyl(C4-C12)sulfonate and their metal salts,
perfluorooctanesulfonic acid diethanol amides,
N-propyl-N-(2-hydroxyethyl- )perfluorooctanesulfone amide,
perfluoroalkyl (C6-C10) sulfoneamidepropyltrimethylammonium salts,
salts of perfluoroalkyl (C6-C10)-N-ethylsulfonylglycin,
monoperfluoroalkyl (C6-C16) ethylphosphates, etc.
[0080] Specific examples of commercially available surfactants
having a fluoroalkyl group include SURFLON S-111, S-112 and S-113,
which are manufactured by Asahi Glass Co., Ltd.; FRORARD FC-93,
FC-95, FC-98 and FC-129, which are manufactured by Sumitomo 3M
Ltd.; UNIDYNEDS-101 and DS-102, which are manufactured by Daikin
Industries, Ltd.; MEGAFACE F-110, F-120, F-113, F-191, F-812 and
F-833 which are manufactured by Dainippon Ink and Chemicals, Inc.;
ECTOP EF-102, 103, 104, 105, 112, 123A, 306A, 501, 201 and 204,
which are manufactured by Tohchem Products Co., Ltd.; FUTARGENT
F-100 and F150 manufactured by Neos; etc.
[0081] Specific examples of cationic surfactants which can disperse
an oil phase including toner constituents in water, include
primary, secondary and tertiary aliphatic amines having a
fluoroalkyl group, aliphatic quaternary ammonium salts such as
perfluoroalkyl (C6-C10) sulfoneamidepropyltrimethylammonium salts,
benzalkonium salts, benzetonium chloride, pyridinium salts,
imidazolinium salts, etc. Specific examples of commercially
available cationic surfactants include SURFLON S-121 (from Asahi
Glass Co., Ltd.); FRORARDFC-135 (from Sumitomo 3MLtd.);
UNIDYNEDS-202 (fromDaikinIndustries, Ltd.); MEGAFACE F-150 and
F-824 (from Dainippon Ink and Chemicals, Inc.); ECTOP EF-132 (from
Tohchem Products Co., Ltd.); FUTARGENT F-300 (from Neos); etc.
[0082] In addition, inorganic compound dispersants such as
tricalcium phosphate, calcium carbonate, titanium oxide, colloidal
silica and hydroxyapatite which are barely insoluble in water can
also be used.
[0083] In addition, it is possible to stably disperse toner
constituents in water using a polymeric protection colloid.
Specific examples of such protection colloids include polymers and
copolymers prepared using monomers such as acids (e.g., acrylic
acid, methacrylic acid, .alpha.-cyanoacrylic acid,
.alpha.-cyanomethacrylic acid, itaconic acid, crotonic acid,
fumaric acid, maleic acid and maleic anhydride), acrylic monomers
having a hydroxyl group (e.g., .beta.-hydroxyethyl acrylate,
.beta.-hydroxyethyl methacrylate, .beta.-hydroxypropyl acrylate,
.beta.-hydroxypropyl methacrylate, .gamma.-hydroxypropyl acrylate,
.gamma.-hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl
acrylate, 3-chloro-2-hydroxypropyl methacrylate,
diethyleneglycolmonoacrylic acid esters,
diethyleneglycolmonomethacrylic acid esters, glycerinmonoacrylic
acid esters, N-methylolacrylamide and N-methylolmethacrylamide),
vinyl alcohol and its ethers (e.g., vinyl methyl ether, vinyl ethyl
ether and vinyl propyl ether), esters of vinyl alcohol with a
compound having a carboxyl group (i.e., vinyl acetate, vinyl
propionate and vinyl butyrate); acrylic amides (e.g, acrylamide,
methacrylamide and diacetoneacrylamide) and their methylol
compounds, acid chlorides (e.g., acrylic acid chloride and
methacrylic acid chloride), and monomers having a nitrogen atom or
an alicyclic ring having a nitrogen atom (e.g., vinyl pyridine,
vinyl pyrrolidone, vinyl imidazole and ethylene imine). In
addition, polymers such as polyoxyethylene compounds (e.g.,
polyoxyethylene, polyoxypropylene, polyoxyethylenealkyl amines,
polyoxypropylenealkyl amines, polyoxyethylenealkyl amides,
polyoxypropylenealkyl amides, polyoxyethylene nonylphenyl ethers,
polyoxyethylene laurylphenyl ethers, polyoxyethylene stearylphenyl
esters, and polyoxyethylene nonylphenyl esters); and cellulose
compounds such as methyl cellulose, hydroxyethyl cellulose and
hydroxypropyl cellulose, can also be used as the polymeric
protective colloid.
[0084] When an acid such as calcium phosphate or a material soluble
in alkaline is used as a dispersant, the calcium phosphate is
dissolved with an acid such as hydrochloric acid and washed with
water to remove the calcium phosphate from the toner particle. In
addition, calcium phosphate may also be removed by an enzymatic
hydrolysis method.
[0085] When a dispersant is used, the dispersant may remain on the
surface of the toner particle. However, the dispersant is
preferably washed and removed after the elongation and/or
crosslinking reaction of the prepolymer with an amine.
[0086] In order to decrease the viscosity of the dispersion medium
including the toner constituents, a solvent which can dissolve the
urea-modified polyester (i) or prepolymer (A) can be used because
the resulting particles have a sharp particle diameter
distribution. The solvent is preferably volatile and has a boiling
point lower than 100.degree. C. so it can be easily removed from
the dispersion after the particles are formed. Specific examples of
such a solvent include toluene, xylene, benzene, carbon
tetrachloride, methylene chloride, 1, 2-dichloroethane,
1,1,2-trichloroethane, trichloroethylene, chloroform,
monochlorobenzene, dichloroethylidene, methyl acetate, ethyl
acetate, methyl ethyl ketone, methyl isobutyl ketone, etc. These
solvents can be used alone or in combination. Among these solvents,
aromatic solvents such as toluene and xylene; and halogenated
hydrocarbons such as methylene chloride, 1,2-dichloroethane,
chloroform, and carbon tetrachloride are preferred. The quantity of
such solvent which is added is from 0 to 300 parts by weight,
preferably from 0 to 100, and more preferably from 25 to 70 parts
by weight, per 100 parts by weight of the prepolymer (A) used. When
such a solvent is used to prepare a particle dispersion, the
solvent is removed therefrom under a normal or reduced pressure
after the particles are subjected to an elongation reaction and/or
a crosslinking reaction of the prepolymer with an amine.
[0087] The elongation and/or crosslinking reaction time depends on
the reactivity of the isocyanate structure of the prepolymer (A)
and amine (B), but is typically from 10 min to 40 hrs, and
preferably from 2 to 24 hrs. The reaction temperature is typically
from 0 to 150.degree. C., and preferably from 40 to 98.degree. C.
In addition, a known catalyst such as dibutyltinlaurate and
dioctyltinlaurate can be used.
[0088] The organic solvent may be removed from an emulsified
dispersion by gradually raising the temperature of the whole
dispersion, thereby completely removing the organic solvent in the
droplet by vaporization. Otherwise, the emulsified dispersion may
be sprayed in dry air, or completely removing a water-insoluble
organic solvent in the droplet to form toner fine particles and
removing a water dispersant by vaporizing. Typically, the dry air
may include atmospheric air, nitrogen gas, carbon dioxide gas, a
gaseous body in which a combustion gas is heated, and particularly
various aerial currents heated to have a temperature of not less
than the boiling point of the solvent used. A spray dryer, a belt
dryer and a rotary kiln can sufficiently remove the organic solvent
in a short time.
[0089] When an emulsified dispersion is washed and dried while
maintaining a wide particle diameter distribution thereof, the
dispersion can be classified to have the desired particle diameter
distribution.
[0090] A cyclone, a decanter, a centrifugal separator, etc. can
remove fine particles in a dispersion liquid. After the dispersion
liquid is dried, the powder can be classified, but for purposes of
efficiency, the liquid is preferably classified. Unnecessary fine
and coarse particles can be recycled to a kneading process to form
particles. The fine and coarse particles may be wet when
recycled.
[0091] The dispersant is preferably removed from the dispersion
liquid, and preferably removed and classified at the same time.
[0092] Heterogeneous particles such as release agent fine
particles, charge controlling fine particles, fluidizing fine
particles and colorant fine particles can be mixed with a toner
powder after being dried. Release of the heterogeneous particles
from composite particles can be prevented by subjecting the mixed
powder to a mechanical stress in order to fix and fuse the
heterogeneous particles on the surface of the composite
particles.
[0093] Specific methods include applying a strong impact on a
mixture with a blade rotating at high-speed, putting the mixture in
a high-speed stream and accelerating the mixture such that the
particles thereof collide each other or composite particles thereof
collide with a collision board, etc. Specific examples of the
apparatus include an ONG MILL from Hosokawa Micron Corp., a
modified I-type mill having a lower pulverizing air pressure from
Nippon Pneumatic Mfg. Co., Ltd., a hybridization system from Nara
Machinery Co., Ltd., a Kryptron System from Kawasaki Heavy
Industries, Ltd., an automatic mortar, etc.
[0094] The toner of the present invention can be used in a
two-component developer in which the toner is mixed with a magnetic
carrier. The amount of the toner is preferably from 1 to 10 parts
by weight per 100 parts by weight of the carrier. Suitable carriers
for use in the two component developer include known carrier
materials such as iron powders, ferrite powders, magnetite powders,
magnetic resin carriers, which have a particle diameter of from
about 20 to about 200 .mu.m. The surface of the carrier may be
coated by a resin. Specific examples of such resins for coating on
the carriers include amino resins such as urea-formaldehyde resins,
melamine resins, benzoguanamine resins, urea resins, and polyamide
resins, and epoxy resins. In addition, vinyl or vinylidene resins
such as acrylic resins, polymethylmethacrylate resins,
polyacrylonitirile resins, polyvinyl acetate resins, polyvinyl
alcohol resins, polyvinyl butyral resins, polystyrene resins,
styrene-acrylic copolymers, halogenated olefin resins such as
polyvinyl chloride resins, polyester resins such as
polyethyleneterephthalate resins and polybutyleneterephthalate
resins, polycarbonate resins, polyethylene resins, polyvinyl
fluoride resins, polyvinylidene fluoride resins,
polytrifluoroethylene resins, polyhexafluoropropylene resins,
vinylidenefluoride-acrylate copolymers,
vinylidenefluoride-vinylfluoride copolymers, copolymers of
tetrafluoroethylene, vinylidenefluoride and other monomers
including no fluorine atom, and silicone resins. An
electroconductive powder may optionally be included in the toner.
Specific examples of such electroconductive powders
includemetalpowders, carbonblacks, titaniumoxide, tinoxide, and
zinc oxide. The average particle diameter of such electroconductive
powders is preferably not greater than 1 .mu.m. When the particle
diameter is too large, it is hard to control the resistance of the
resulting toner.
[0095] The toner of the present invention can also be used as a
one-component magnetic developer or a one-component non-magnetic
developer.
[0096] FIG. 1 provides a schematic view of one embodiment of a
process cartridge according to the present invention. The process
cartridge may be detachably installed in a copier, and comprises a
photoreceptor (1), a charger (2), and image developer (3), and a
cleaner (4). In the present invention, the process cartridge
includes the photoreceptor and at least one of the charger, image
developer, and cleaner.
[0097] In an image forming apparatus including the process
cartridge of the present invention, the photoreceptor is rotated at
a predetermined peripheral speed. The peripheral surface of the
photoreceptor is uniformly positively or negatively charged by the
charger when rotated. Then, the peripheral surface of the
photoreceptor is irradiated with imagewise light by a slit
irradiator, a laser beam scanning irradiator, etc., to form an
electrostatic latent image thereon. The electrostatic latent image
is developed by an image developer to form a toner image on the
peripheral surface of the photoreceptor. The toner image is
transferred onto a transfer sheet fed between the photoreceptor and
a transferer from a paper feeder in sync with a rotation of the
photoreceptor. The transfer sheet on which the toner image is
transferred separates from the peripheral surface of the
photoreceptor and fed to an image fixer to fix the toner image
thereon, and fed out of the apparatus as a duplicate copy. The
peripheral surface of the photoreceptor is cleaned by a cleaner to
remove residual toner after it is transferred, and is discharged to
be prepared for forming the following image.
[0098] Having generally described this invention, further
understanding can be obtained by reference to certain specific
examples which are provided herein for the purpose of illustration
only and are not intended to be limiting. In the descriptions in
the following examples, the numbers represent weight ratios in
parts, unless otherwise specified.
EXAMPLES
Production Example 1
[0099] 683 parts of water, 11 parts of a sodium salt of an adduct
of a sulfuric ester with ethyleneoxide methacrylate (ELEMINOL RS-30
from Sanyo Chemical Industries, Ltd.), 83 parts of styrene, 83
parts of methacrylate, 110 parts of butylacrylate and 1 part of
ammonium persulfate were mixed in a reactor vessel including a
stirrer and a thermometer, and the mixture was stirred for 15 min
at 400 rpm to prepare a white emulsion therein. The white emulsion
was heated to a temperature of 75.degree. C. and reacted for 5 hrs.
Then, 30 parts of an aqueous solution of persulfate ammonium having
a concentration of 1% were added thereto and the mixture was
reacted for 5 hrs at 75.degree. C. to provide an aqueous dispersion
[a fine particle dispersion liquid 1] of a vinyl resin (a copolymer
of a sodium salt of an adduct of
styrene-methacrylate-butylacrylate-sulfuric ester with
ethyleneoxide methacrylate). The fine particle dispersion liquid 1
was analyzed by a LA-920 device, and the volume-average particle
diameter thereof was 105 nm. A portion of the fine particle
dispersion liquid 1 was dried to isolate a resin component
therefrom. The resin component had a Tg of 59.degree. C. and
weight-average molecular weight of 150,000.
Production Example 2
[0100] 990 parts of water, 83 parts of the fine particle dispersion
liquid 1, 37 parts of an aqueous solution of sodium
dodecyldiphenyletherdisulfon- ate having a concentration of 48.5%
(ELEMINOL MON-7 from Sanyo Chemical Industries, Ltd.) and 90 parts
of ethyl acetate were mixed and stirred to prepare an aqueous
liquid [an aqueous phase 1].
Production Example 3
[0101] 319 parts of an adduct of bisphenol A with 2 moles of
propyleneoxide, 449 parts of an adduct of bisphenol A with 2 moles
of ethyleneoxide, 243 parts terephthalic acid, 53 parts of adipic
acid and 2 parts of dibutyltinoxide were mixed and reacted in a
reactor vessel including a cooling pipe, a stirrer and a nitrogen
lead-in pipe for 8 hrs at a normal pressure and 230.degree. C.
Further, after the mixture was depressurized by 10 to 15 mm Hg and
reacted for 5 hrs, 7 parts of trimellitic acid anhydride was added
thereto and reacted for 2 hrs at 180.degree. C. and a normal
pressure to prepare low-molecular-weight polyester 1. The
low-molecular-weight polyester 1 had a number-average molecular
weight of 1,900, a weight-average molecular weight of 6,100, a Tg
43.degree. C. and an acid value of 1.1.
Production Example 4
[0102] 682 parts of an adduct of bisphenol A with 2 moles of
ethyleneoxide, 81 parts of an adduct of bisphenol A with 2 moles of
propyleneoxide, 283 parts terephthalic acid, 22 parts of
trimellitic acid anhydride and 2 parts of dibutyltinoxide were
mixed and reacted in a reactor vessel including a cooling pipe, a
stirrer and a nitrogen lead-in pipe for 8 hrs at a normal pressure
and 230.degree. C. Then, the mixture was depressurized by 10 to 15
mm Hg and reacted for 5 hrs to provide an intermediate polyester 1.
The intermediate polyester 1 had a number-average molecular weight
of 2,100, a weight-average molecular weight of 9,500, a Tg
55.degree. C. and an acid value of 0.5 and a hydroxyl value of
51.
[0103] Next, 410 parts of the intermediate polyester 1, 89 parts of
isophoronediisocyanate and 500 parts of ethyl acetate were reacted
in a reactor vessel including a cooling pipe, a stirrer and a
nitrogen lead-in pipe for 5 hrs at 100.degree. C. to provide a
prepolymer 1. The prepolymer 1 includes a free isocyanate in an
amount of 1.53% by weight.
Production Example 5
[0104] 170 parts of isophorondiamine and 75 parts of methyl ethyl
ketone were reacted at 50.degree. C. for 5 hrs in a reaction vessel
including a stirrer and a thermometer to provide a ketimine
compound 1. The ketimine compound 1 had an amine value of 418.
Example 1
[0105] 30 parts of water, 50 parts of C.I. Pigment Blue 15:3
(LIONOL BLUE FG-7351 from Toyo Ink Mfg. Co., Ltd.), 50 parts of the
low-molecular-weight polyester 1 and 5 parts of a pigment
dispersant (Solsperse S24000sc from Avecia KK) were mixed in a
Henschel mixer from Mitsui Mining Co., Ltd. to provide a mixture
which is a pigment aggregate including water. After the mixture was
kneaded by a two-roll mill at 130.degree. C. for 45 min, the
mixture was rolled, cooled and pulverized by a pulverizer to
provide a cyan master batch 1. 378 parts of the
low-molecular-weight polyester 1, 110 parts of synthetic ester wax,
22 parts of charge controlling agent (salicylic acid metal complex
E-84 from Orient Chemical Industries Co., Ltd.) and 947 parts of
ethyl acetate were mixed in a reaction vessel including a stirrer
and a thermometer. The mixture was heated to have a temperature of
80.degree. C. while stirred. After the temperature of 80.degree. C.
was maintained for 5 hrs, the mixture was cooled to have a
temperature of 30.degree. C. in an hour. Then, 500 parts of the
cyan master batch 1 and 500 parts of ethyl acetate were added to
the mixture and mixed for 1 hr to provide a cyan material solution
1.
[0106] 1,324 parts of the cyan material solution 1 were transferred
into another vessel, and a pigment and a wax thereof were dispersed
by a bead mill (an ultra visco mill from Imecs Co., Ltd. filled
with zirconia beads having a diameter of 0.5 mm by 80 volume %
under conditions of 3 passes at a liquid feeding speed of 1 kg/hr
and a disk peripheral speed of 6 m/sec. Next, 1,324 parts of an
ethyl acetate solution of the low-molecular-weight polyester 1
having a concentration of 65% were added to the cyan material
solution 1 and the mixture was milled in the bead mill at one time
to provide a cyan pigment and wax dispersion liquid 1. The cyan
pigment and wax dispersion liquid 1 had a solid content
concentration of 50% (130.degree. C. for 30 min).
[0107] 664 parts of the cyan pigment and wax dispersion liquid 1,
139 parts of the prepolymer 1 and 5.9 parts of the ketimine
compound 1 were mixed in a vessel with a TK homomixer from TOKUSHU
KIKA KOGYO CO., LTD. at 5,000 rpm for 1 min. 1,200 parts of the
aqueous phase were added to the mixture and mixed with the TK
homomixer at 13,000 rpm for 20 min to provide a cyan emulsified
slurry 1.
[0108] The cyan emulsified slurry 1 was put in a vessel including a
stirrer and a thermometer. After a solvent was removed from the
cyan emulsified slurry 1 at 30.degree. C. for 8 hrs, the slurry was
aged at 45.degree. C. for 4 hrs to provide a cyan dispersion slurry
1.
[0109] After the cyan dispersion slurry 1 was filtered under
reduced pressure, 100 parts of ion exchanged water were added to
the filtered cake and mixed with the TK homomixer at 12,000 rpm for
10 min, and the mixture was filtered.
[0110] Then, 100 parts of an aqueous solution of sodium hydrate
having a concentration of 10% were added to the filtered cake and
mixed with the TK homomixer at 12,000 rpm for 30 min, and the
mixture was filtered under reduced pressure.
[0111] Then, 100 parts of 10% hydrochloric acid were added to the
filtered cake and mixed with the TK homomixer at 12, 000 rpm for 10
min, and the mixture was filtered.
[0112] In addition, 300 parts of ion exchange water were added to
the filtered cake and mixed with the TK homomixer at 12,000 rpm for
10 min, and the mixture was filtered twice to provide a cyan
filtered cake 1.
[0113] The cyan filtered cake 1 was dried in an air drier at
45.degree. C. for 48 hrs and sieved with a mesh having an opening
of 75 .mu.m to provide toner particles. Each 0.5 parts of
hydrophobic silica and hydrophobic titania were mixed with 100
parts of the toner particles in a Henschel mixer to provide a cyan
toner 1.
Example 2
[0114] 30 parts of water, 50 parts of C.I. Pigment Red 122 (Magenta
R from Toyo Ink Mfg. Co., Ltd.), 50 parts of the
low-molecular-weight polyester 1 and 8 parts of a pigment
dispersant (Solsperse S24000sc from Avecia KK) were mixed in a
Henschel mixer from Mitsui Mining Co., Ltd. to provide a mixture
which is a pigment aggregate including water. After the mixture was
kneaded with a two-roll mill at 130.degree. C. for 45 min, the
mixture was rolled, cooled and pulverized with a pulverizer to
provide a magenta master batch 1.
[0115] Then, the procedures for preparing the cyan toner 1 in
Example 1 were repeated except for changing the cyan master batch 1
to the magenta master batch 1 to provide a magenta toner 1.
Example 3
[0116] 30 parts of water, 50 parts of C.I. Pigment Yellow 155
(Toner Yellow 3GP from Clariant Japan KK), 50 parts of the
low-molecular-weight polyester 1 and 6 parts of a pigment
dispersant (Solsperse S24000sc from Avecia KK) were mixed in a
Henschel mixer from Mitsui Mining Co., Ltd. to provide a mixture
which is a pigment aggregate including water. After the mixture was
kneaded by a two-roll mill at 130.degree. C. for 45 min, the
mixture was rolled, cooled and pulverized with a pulverizer to
provide a yellow master batch 1.
[0117] Then, the procedures for preparing the cyan toner 1 in
Example 1 were repeated except for changing the cyan master batch 1
to the yellow master batch 1 to provide a yellow toner 1.
Example 4
[0118] 30 parts of water, 50 parts of carbon black (Printex 60 from
Daicel-Degussa Ltd.), 50 parts of the low-molecular-weight
polyester 1 and 4 parts of a pigment dispersant (Solsperse S24000sc
from Avecia KK) were mixed in a Henschel mixer from Mitsui Mining
Co., Ltd. to provide a mixture which is a pigment aggregate
including water. After the mixture was kneaded by a two-roll mill
at 130.degree. C. for 45 min, the mixture was rolled, cooled and
pulverized with a pulverizer to provide a black master batch 1.
[0119] Then, the procedures for preparing the cyan toner 1 in
Example 1 were repeated except for changing the cyan master batch 1
to the black master batch 1 to provide a black toner 1.
Example 5
[0120] 30 parts of water, 50 parts of C.I. Pigment Blue 15:3
(LIONOL BLUE FG-7351 from Toyo Ink Mfg. Co., Ltd.), 50 parts of the
low-molecular-weight polyester 1, 5 parts of a pigment dispersant
(Solsperse S24000sc from Avecia KK) and 1.25 parts of a pigment
dispersion auxiliary agent (Solsperse S5000 from Avecia KK) mixed
in a Henschel mixer from Mitsui Mining Co., Ltd. to provide a
mixture which is a pigment aggregate including water. After the
mixture was kneaded by a two-roll mill at 130.degree. C. for 45
min, the mixture was rolled, cooled and pulverized with a
pulverizer to provide a cyan master batch 2.
[0121] Then, the procedures for preparing the cyan toner 1 in
Example 1 were repeated except for changing the cyan master batch 1
to the cyan master batch 2 to provide a cyan toner 2.
Example 6
[0122] 30 parts of ethyl acetate, 50 parts of C.I. Pigment Blue
15:3 (LIONOL BLUE FG-7351 from Toyo Ink Mfg. Co., Ltd.), 50 parts
of the low-molecular-weight polyester 1 and 5 parts of a pigment
dispersant (Solsperse S24000sc from Avecia KK) were mixed in a
Henschel mixer from Mitsui Mining Co., Ltd. to provide a mixture
which is a pigment aggregate including water. After the mixture was
kneaded by a two-roll mill at 130.degree. C. for 45 min, the
mixture was rolled, cooled and pulverized with a pulverizer to
provide a cyan master batch 3.
[0123] Then, the procedures for preparing the cyan toner 1 in
Example 1 were repeated except for changing the cyan master batch 1
to the cyan master batch 3 to provide a cyan toner 3.
Comparative Example 1
[0124] 578 parts of the low-molecular-weight polyester 1, 110 parts
of synthetic ester wax, 22 parts of charge a controlling agent
(salicylic acid metal complex E-84 from Orient Chemical Industries
Co., Ltd.) and 947 parts of ethyl acetate were mixed in a reaction
vessel including a stirrer and a thermometer. The mixture was
heated to a temperature of 80.degree. C. while being stirred. After
the temperature of 80.degree. C. was maintained for 5 hrs, the
mixture was cooled to a temperature of 30.degree. C. in an hour.
Then, 300 parts of C.I. Pigment Blue 15:3 (LIONOL BLUE FG-7351 from
Toyo Ink Mfg. Co., Ltd.) and 500 parts of ethyl acetate were added
to the mixture and mixed for 1 hr to provide a comparative cyan
material solution 1.
[0125] 1,324 parts of the comparative cyan material solution 1 were
transferred into another vessel, and a pigment and a wax were
dispersed with a bead mill (an ultra visco mill from Imecs Co.,
Ltd. filled with zirconia beads having a diameter of 0.5 mm by 80
volume % under conditions of 3 passes at a liquid feeding speed of
1 kg/hr and a disk peripheral speed of 6 m/sec. Next, 1,324 parts
of an ethyl acetate solution of the low-molecular-weight polyester
1 having a concentration of 65% were added to the comparative cyan
material solution 1 and the mixture was milled with the bead mill
at one time to provide a comparative cyan pigment and wax
dispersion liquid 1. The comparative cyan pigment and wax
dispersion liquid 1 had a solid content concentration of 50%
(130.degree. C. for 30 min).
[0126] Then, the procedures for preparing the cyan toner 1 in
Example 1 were repeated except for changing the cyan pigment and
wax dispersion liquid 1 to the comparative cyan pigment and wax
dispersion liquid 1 to provide a comparative cyan toner 1.
Comparative Example 1
[0127] 30 parts of water, 50 parts of C.I. Pigment Blue 15:3
(LIONOL BLUE FG-7351 from Toyo Ink Mfg. Co., Ltd.) and 50 parts of
the low-molecular-weight polyester were mixed in a Henschel mixer
from Mitsui Mining Co., Ltd. to provide a mixture which is a
pigment aggregate including water. After the mixture was kneaded
with a two-roll mill at 130.degree. C. for 45 min, the mixture was
rolled, cooled and pulverized with a pulverizer to provide a
comparative cyan master batch 2.
[0128] Then, the procedures for preparing the cyan toner 1 in
Example 1 were repeated except for changing the cyan master batch 1
to the comparative cyan master batch 2 to provide a comparative
cyan toner 2.
[0129] Evaluation Items
[0130] (a) Particle Diameter
[0131] Specific examples of a toner particle-diameter distribution
measuring device using the Coulter counter method include a Coulter
Counter TA-II and a Coulter Multisizer II from Beckman Coulter,
Inc. The measuring method will be explained.
[0132] First, 0.1 to 5 ml of a surfactant, preferably an
alkylbenzenesulfonic acid dispersant were added in 100 to 150 ml of
an electrolytic aqueous solution. The electrolytic aqueous solution
is a sodium chloride aqueous solution using primary sodium chloride
and having a concentration of 1%, such as ISOTON-II from Beckman
Coulter, Inc. 2 to 20 mg of toner particles were added in the
mixture. The electrolytic aqueous solution including the toner
particles was dispersed for 1 to 3 min by an ultrasonic disperser.
The toner particles or volume and number were measured by the
above-mentioned measuring device using an aperture of 100 .mu.m to
determine the volume and number distributions of the toner.
Volume-average (Dv) and number-average (Dn) particle diameters of
the toner were determined from the distributions.
[0133] 13 channels, i.e., 2.00 to less than 2.52 .mu.m; 2.52 to
less than 3.17 .mu.m; 3.17 to less than 4.00 .mu.m; 4.00 to less
than 5.04 .mu.m; 5.04 to less than 6.35 .mu.m; 6.35 to less than
8.00 .mu.m; 8.00 to less than 10.08 .mu.m; 10.08 to less than 12.70
.mu.m; 12.70 to less than 16.00 .mu.m; 16.00 to less than 20.20
.mu.m; 20.20 to less than 25.40 .mu.m; 25.40 to less than 32.00
.mu.m; and 32.00 to less than 40.30 .mu.m were used.
[0134] (b) Amount of Charge
[0135] 6 g of the toner was put in a sealed metallic cylinder and
blown to determine the amount of charge thereof. The toner
concentration was from 4.5 to 5.5% by weight.
[0136] (c) Circularity
[0137] A flow-type particle image analyzer FPIA-2000 from SYSMEX
CORPORATION can measure the average circularity. The specific
measuring method includes adding 0.1 to 0.5 ml of a surfactant,
preferably an alkylbenzenesulfonic acid dispersant in 100 to 150 ml
of water from which impure solid materials were previously removed;
adding 0.1 to 0.5 g of the toner in the mixture; dispersing the
mixture including the toner with an ultrasonic disperser for 1 to 3
min to provide a dispersion liquid having a concentration of from
3,000 to 10,000 pieces/.mu.l; and measuring the toner shape and
distribution with the above-mentioned measuring device.
[0138] (d) Haze Factor
[0139] An image was produced on an OHP sheet type PPC-DX from Ricoh
Company, Ltd. in a full-color copier PRETER 550 from Ricoh Company,
Ltd. by the OHP mode when the fixing roller had a surface
temperature of 160.degree. C. such that the toner is developed by
1.0.+-.0.1 mg/cm.sup.2 thereon, which is modified to have a higher
spring pressure of the fixer and a nip width of 1.6 times.
[0140] The haze factor of the image was measure by a direct reading
haze factor computer HGM-2DP from Suga Test Instruments Co.,
Ltd.
[0141] The haze factor is also called cloudiness and represents the
transparency of a toner. The smaller the haze factor, the higher
the transparency. The colorability of a toner on an OHP sheet and
an underlayer thereof improves, and the resulting image has wider
color reproducibility. The haze factor is preferably not greater
than 30%, and more preferably not greater than 20%.
[0142] (e) Glossiness
[0143] An image was produced on an a transfer sheet type 6000-70W
from Ricoh Company, Ltd. in a full-color copier PRETER 550 from
Ricoh Company, Ltd. when the fixing roller had a surface
temperature of 160.degree. C. such that the toner is developed by
1.0.+-.0.1 mg/cm.sup.2 thereon, which is modified to have a higher
spring pressure of the fixer and a nip width of 1.6 times.
[0144] The glossiness of the image was measured by a gloss meter
from Nippon Denshoku Industries Co., Ltd. at an incident angle of
600. The higher the glossiness, the more the gloss. Brilliant
images having good color reproducibility need a glossiness of not
less than 10%. Full-color copy images preferably have a glossiness
of from about 10 to 30%.
[0145] (f) Pigment Dispersion Diameter in a Toner
[0146] A cross section of an ultra thin slice of a toner is
photographed using a transmission electron microscope H-9000H from
Hitachi, Ltd. at 100,000 magnifications. An average value of the
dispersion diameters of randomly chosen 100 pigments in the
photograph was determined. The dispersion diameter of a particle
was an average of the longest and shortest diameters, and an
aggregate was regarded as a particle.
[0147] (g) Image Density
[0148] The image density of a solid image was measured by X-Rite
from X-Rite, Inc. 5 points of each solid color image were measured
and an average value of the 5 points was determined for each color.
An image density of not less than 1.4 is a practicable level.
[0149] (h) Image Granularity
[0150] A photo image was produced in a single color and the
granularity of the image was visually evaluated.
[0151] (i) Background Fouling
[0152] Background fouling of a transfer sheet was visually
evaluated.
[0153] (j) Toner Scattering
[0154] Toner contamination in a copier was visually evaluated.
[0155] In addition, as an endurance test, before and after 50,000
images of a chart having an image area of 5% were produced by
modified IPSIO color 8000 from Ricoh Company, Ltd. The evaluation
item (b) was performed, and (h) and (j) were performed after the
test.
[0156] The properties of the toners are shown in Table 1 and
evaluation results thereof are shown in Table 2.
[0157] Any toners in the Examples included finely and uniformly
dispersed colorants and produced images having good image
properties. The toner in the Comparative Example 1 included a
pigment without a dispersant, and therefore the pigment was not
well dispersed and had a large dispersion diameter. Accordingly,
the toner produced images having poor image density and haze
factor, and the charge stability thereof deteriorated. The toner in
the Comparative Example 2 also included a pigment without a
dispersant although it including a master batch pigment, and
therefore the properties thereof were not satisfactory.
1 TABLE 1 Master batch Pigment dispersion Pigment auxiliary Pigment
dispersant agent Solvent Ex. 1 P.B. 15:3 S24000sc Not used Water
Ex. 2 P.R. 122 S24000sc Not used Water Ex. 3 P.Y. 155 S24000sc Not
used Water Ex. 4 Printex 60 S24000sc Not used Water Ex. 5 P.B. 15:3
S24000sc S5000 Water Ex. 6 P.B. 15:3 S24000sc Not used Ethyl
acetate Com. Ex. 1 P.B. 15:3 Not used Not used Only pigment Com.
Ex. 2 P.B. 15:3 Not used Not used Water Pigment Dispersion
Dispersion 0.7 .mu.m or diameter more Particle Diameter Average
(.mu.m) (number %) Dv (.mu.m) Dv/Dn circularity Ex. 1 0.45 4.4 5.3
1.19 0.964 Ex. 2 0.38 4.0 5.1 1.23 0.978 Ex. 3 0.41 4.2 5.0 1.15
0.973 Ex. 4 0.22 2.8 5.5 1.14 0.985 Ex. 5 0.38 3.7 5.2 1.21 0.969
Ex. 6 0.42 4.3 4.9 1.24 0.965 Com. Ex. 1 0.75 75.0 5.0 1.18 0.971
Com. Ex. 2 0.63 22.3 5.4 1.22 0.966
[0158]
2 TABLE 2 Glossiness Haze factor Image Granulari- (%) (%) density
ty Ex. 1 21 16 1.8 .circleincircle. Ex. 2 22 14 2.0
.circleincircle. Ex. 3 25 15 1.9 .circleincircle. Ex. 4 19 -- 2.1
.circleincircle. Ex. 5 24 18 2.0 .circleincircle. Ex. 6 23 17 1.9
.circleincircle. Com. Ex. 1 17 35 1.3 .largecircle. Com. Ex. 2 16
28 1.4 .largecircle. Background Toner Charge Amount fouling
scattering After 50,000 After 50,000 After 50,000 images were
images were images were Initial produced produced produced Ex. 1 27
21 .circleincircle. .circleincircle. Ex. 2 24 18 .circleincircle.
.circleincircle. Ex. 3 30 26 .circleincircle. .circleincircle. Ex.
4 29 17 .circleincircle. .circleincircle. Ex. 5 28 20
.circleincircle. .circleincircle. Ex. 6 26 19 .circleincircle.
.circleincircle. Com. Ex. 1 18 10 .DELTA. .DELTA. Com. Ex. 2 20 14
.largecircle. .DELTA.
[0159] This document claims priority and contains subject matter
related to Japanese Patent Application No. 2002-289090 filed on
Oct. 1, 2002, and which is incorporated herein by reference.
[0160] Having now fully described the invention, it will be
apparent to one of ordinary skill in the art that many changes and
modifications can be made thereto without departing from the spirit
and scope of the invention as set forth therein.
* * * * *